In process automation technology, field devices are often applied, which serve for registering and/or influencing process variables. Serving for registering process variables are sensors, such as, for example, fill level measuring devices, flow measuring devices, pressure- and temperature-measuring devices, pH redox-potential measuring devices, conductivity measuring devices, etc., which register the respective process variables, fill level, flow, pressure, temperature, pH-value, and conductivity. Serving for influencing process variables are actuators, such as, for example, valves or pumps, via which the flow of a liquid in a section of pipeline, respectively the fill level in a container, can be changed. Referred to, in principle, as field devices are all devices, which are applied near to the process and which deliver, or process, information relevant to the process. Besides the above mentioned sensors and actuators, referred to as field devices are generally also units, which are connected directly to a fieldbus and serve for communication with the superordinated units, such as e.g. remote I/Os, gateways, linking devices and wireless adapters. A large number of such field devices are manufactured and sold by the Endress+Hauser group of companies.
Before start-up and for modifying the functioning of the field device, such must be parametered. For parametering, especially for reading and/or writing parameters, operating tools are applied. Such operating tools are, in such case, implemented, as a rule, in a communication unit separate from the respective field device and communicate with the field device via a fieldbus or via a service interface of the field device. In given cases, communication via the service interface is based on a manufacturer-specific protocol.
In order that between an operating tool connected for communication with the field device and the field device no cyclic adjustment of all data, especially parameters provided in the field device, must occur, one distinguishes between static parameters and dynamic parameters of a field device. Dynamic parameters, such as, for example, measured values, status information, error reports, etc., change their values especially as a function of the process variables to be measured or to be influenced and/or as a function of the state of the field device. Dynamic parameters of the field device are cyclically read, respectively, in the case of an actuator movement, cyclically written, as a rule, in the context of a cyclic communication by a superordinated unit, which performs the process control. In contrast, static parameters change only when something changes as regards the configuration of the field device. Such a change of the device configuration occurs, as a rule, by the servicing of the field device via an operating tool or via an onsite servicing. Such servicing is, as a rule, performed by a user or by a superordinated system. A cyclic read-out of static parameters is, in such case, not provided.
The opportunity for a user, respectively operator, or a superordinated system to change the device configuration, however, introduces the danger that the device will not be correctly parametered, so that then the field device will malfunction. In this case, the only recourse is often to return all static parameters to their state at the time of delivery. In such case, it is especially annoying that many subsequent settings, thus changes of the device configuration by means of static parameters, must be abandoned and, moreover, even a service visit can become necessary.
Options are known from the state of the art, which provide for securing the performed parameter changes in different ways. However, in all known methods, the user, respectively operator, must perform this securing. Often, in the case of a problem, there is no suitable securing, and the only recourse is to return the parameters to the state they were in at delivery. This leads to the fact that the field device cannot continue its operation or operation is continued only after an extended pause, during which the appropriate parameters are reintroduced.